1. Field of the Invention
The present invention is related to earth formation drilling operations, and more particularly, to methods and system apparatus for predicting performance of a drilling system for a given formation.
2. Discussion of the Related Art
From the very beginning of the oil and gas well drilling industry, as we know it, one of the biggest challenges has been the fact that it is impossible to actually see what is going on downhole. There are any number of downhole conditions and/or occurrences which can be of great importance in determining how to proceed with the operation. It goes without saying that all methods for attempting to assay such downhole conditions and/or occurrences are indirect. To that extent, they are all less than ideal, and there is a constant effort in the industry to develop simpler and/or more accurate methods.
In general, the approach of the art has been to focus on a particular downhole condition or occurrence and develop a way of assaying that particular condition or occurrence. For example, U.S. Pat. No. 5,305,836, discloses a method whereby the wear of a bit currently in use can be electronically modeled, based on the lithology of the hole being drilled by that bit. This helps a drilling operator determine when it is time to replace the bit.
The process of determining what type of bit to use in a given part of a given formation has, traditionally, been, at best, based only on very broad, general considerations, and at worst, more a matter of art and guess work than of science.
Other examples could be given for other kinds of conditions and/or occurrences.
Furthermore, there are still other conditions and/or occurrences which would be helpful to know. However, because they are less necessary, and in view of the priority of developing better ways of assaying those things which are more important, little or no attention has been given to methods of assaying these other conditions.